Spin spiral calculation and periodic boundary condition

[wenteli]

Dear vasp community,

I am using VASP to do noncollinear spin spiral calculation. I am reading the documentation on the vasp wiki website: https://cms.mpi.univie.ac.at/wiki/index ... in_spirals. In the “Initialization of the magnetic subsystem” section, vasp gives two examples of initial magnetic moment. For the second example, I am confused whether it breaks the periodic boundary condition. You have three cells and the rotation angle is based on q spiral vector. In the POSCAR file, should I only include Cell 1 or both Cell 1&2? If it is the former, then it breaks the periodic boundary condition because Cell 2 spin is different with Cell 1. I am not sure whether my understanding is correct or not and am willing to hear from you.

Thank you all so much for your help.